75 850 ES clutch

click · Apr 11, 2010

pvisseriii said:
I believe a 15 degree lean to be ideal, but the side stand seems sufficient.

:mrgreen: nuts I had the bike at 14 1/2 degrees

I'll have to strip the entire engine or just scrap this one & get another :mrgreen:

I was filling the primary chaincase with the bike on the centre stand, explains why it took 375ml of oil!, I'll drain out the excess & check it over the next few weeks to see if any more leaks in there.

Kevin

L.A.B. · Apr 11, 2010

click said:
I've seen that posted before about the 1/16' hole in the gearbox inspection cover to relieve a bit of pressure, I think I have a small enough drill bit in my workshop (also known as a shed!)

Your MkIII's gearbox should already have a breather (a small brass 'bush' in the top of the inner cover, directly inboard of where the cable enters the box) so drilling the inspection cover shouldn't be necessary? http://www.oldbritts.com/12_065199.html

I can't really see how pressure could build up in the box anyway? As the clutch cable entry isn't sealed, and even if it was, any excess pressure would escape up the cable.

grandpaul · Apr 11, 2010

"Parking" the pistons at TDC will slow the migration of oil through the crank to the sump when the bike is left to sit. Cures wet-sumping on some bikes...

swooshdave · Apr 11, 2010

L.A.B. said:
click said:

I've seen that posted before about the 1/16' hole in the gearbox inspection cover to relieve a bit of pressure, I think I have a small enough drill bit in my workshop (also known as a shed!)

Click to expand...

Your MkIII's gearbox should already have a breather (a small brass 'bush' in the top of the inner cover, directly inboard of where the cable enters the box) so drilling the inspection cover shouldn't be necessary? http://www.oldbritts.com/12_065199.html

I can't really see how pressure could build up in the box anyway? As the clutch cable entry isn't sealed, and even if it was, any excess pressure would escape up the cable.

I've heard that before but it's seems like a path with a lot of resistance.

rgrigutis · Apr 11, 2010

You can make your own diaphragm spring Tool w/ a steel electrical box/ 1/2" bolt and nut.

L.A.B. · Apr 12, 2010

swooshdave said:
I've heard that before but it's seems like a path with a lot of resistance.

I can't really see that a loose fitting clutch cable resting in an open abutment in the casing is likely to offer much, if any, resistance to escaping air from the box , I think that would be stretching the imagination just a little too far in my opinion.

swooshdave · Apr 12, 2010

L.A.B. said:
swooshdave said:

I've heard that before but it's seems like a path with a lot of resistance.

Click to expand...

I can't really see that a loose fitting clutch cable resting in an open abutment in the casing is likely to offer much, if any, resistance to escaping air from the box , I think that would be stretching the imagination just a little too far in my opinion.

So you assume that Norton added the MkIII gearbox breather for absolutely no reason?

Gearbox leaks are notorious. Is it just failing O-rings? Or something else?

After 40 years it seems like we might actually have a handle on the engine leaks, perhaps now it's time to move to the gearbox. :mrgreen:

Hortons Norton · Apr 12, 2010

Dave I would say that's what causes most of the leaks we see, The o-rings just don't hold very long. I think that's why the seal modification is so popular, I had it done on the 72 and haven't seen any oil on the cover. I agree with L.A.B. it's hard to imagine air would not make it by the cable, But I did fit a MKIII inner cover when I rebuilt the trans. for the 72 that has the brass breather tube on it. I also put Dave's seal on the end of the main shaft too.

75 850 ES clutch

click

L.A.B.

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grandpaul

swooshdave

rgrigutis

L.A.B.

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swooshdave

Hortons Norton

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